The invention relates to an automated collar-forming drill mechanism, comprising a rotatable drive shaft, a tool head mounted on the end of the drive shaft, an actuator for rotating the drive shaft, transfer means for carrying the drive shaft and the tool head back and forth in axial direction, said tool head comprising a drill for drilling a hole in the wall of a workpiece, such as a pipe, as the tool head is carried in one axial direction during a drilling operation, and collar-forming pegs adapted to extend below the hole rims and to extract the hole-encircling wall material for a collar as the tool head is carried in the opposite axial direction during a collar-forming operation.
This type of collar-forming drill devices are prior known e.g. from Patent publications U.S. Pat. Nos. 3,884,060 and 3,592,038. In these prior art mechanisms, the working actions are based on designing the drive shaft as a screw spindle and on maneuvering the struts seated against a pipe to be machined by means of a bifurcated nut element, which is engageable with a rotating spindle provided with a left-hand helix. This arrangement involves a number of drawbacks. Operating speeds and directions are dependent on the rotational speed and direction of the spindle. Thus, the motions or actions cannot be optimized. In addition, the nut and the screw spindle wear in use, which reduces the service life of the mechanism or results repeatedly in a labour-intensive and expensive maintenance action.
It is an object of the invention to provide an automated collar-forming drill mechanism improved in such a way that the operating speeds, operating ranges or distances, speed variation points, and reversing points of a tool head may all be selected as desired and provided with versatile regulating options, in addition to which the wear and maintenance demand are minimal for equipment responsible for power transmission.
This object is achieved on the basis of the characterizing features set forth in the appended claim 1. The dependent claims disclose preferred embodiments of the invention.